[petsc-dev] [petsc-users] EPSSolve in a loop

[Jed Brown]

Matthew Knepley <knepley at gmail.com> writes:

> On Sat, May 4, 2013 at 6:40 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:
>
>> Dharmendar Reddy <dharmareddy84 at gmail.com> writes:
>>
>> > There is no CHKMEMQ statements.
>>
>> I meant inside the VecScale() implementation.  It turns out that
>> PetscStackCall(), which is used around all BLAS/Lapack functions, among
>> others, currently includes CHKMEMQ.
>>
>> CHKMEMQ walks all allocations to check for memory corruption.  It can be
>> rather time consuming when many objects (or other small allocations)
>> occur.  If you run with '-malloc 0', the performance problem will go
>> away.  When PETSc is configured --with-debugging=0, CHKMEMQ does nothing
>> unless you pass '-malloc' (so it'll be fast by default in optimized
>> mode).
>>
>> petsc-dev, is this performance degradation of multiple orders of
>> magnitude really tolerable?  Should we turn off malloc checking around
>> BLAS/Lapack functions unless the user passes an extra flag (but leave
>> sentinel checking around user functions because that's where almost all
>> the memory bugs are)?
>>
>
> I was for eliminating these before.

I didn't realize that never got any action.  Here's a pull request to
fix it.

https://bitbucket.org/petsc/petsc/pull-request/33/consolidate-petscstack-and-add/diff